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Wondering why I dont really hear people talkinng about this 354 stroker kit for a 302. Its a 3.47" Stroke crank with a 5.4 rod in a .030 302 block.

Are there some problems with this set up. Came across it while researching the 347 I am trying to get together for my street / strip car.

Any thoughts?
 

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You can theoretically get 354 cu" with a 3.47"stroke and a 4.030" bore.
You might have to use a piston with a lower compression height. The problem that you run into with extreme stroker kits is the side loads placed on the pistons from the short rods and high angular loads the firing stroke places on them. If there is a stroker kit available it probably won't be any better at generating hp or torque than the 347 cu" stroker kit.
Paul
 

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Actually, I think it is the 355 build up, at least PAW sells/sold it...
 

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What you are talking about is an overbore in excess of the "standard" .030. Most like based on a .060 overbore. Some, thickwalled block will take that much.

Engine with bore of 4.000 and stroke of 3.4 is 341.81 CID
Engine with bore of 4.015 and stroke of 3.4 is 344.37 CID
Engine with bore of 4.030 and stroke of 3.4 is 346.95 CID
Engine with bore of 4.040 and stroke of 3.4 is 348.68 CID
Engine with bore of 4.060 and stroke of 3.4 is 352.14 CID
Engine with bore of 4.080 and stroke of 3.4 is 355.62 CID

FMS has blocks (302-based) that can go to 360 ~ 370, with the right combination of crank and OB ... least ways, thats the way I heard it.


So 355, 354 or 357 would fall into the range of "number games" played by rounding up or down.

Displacment is figured based on "swept area". so regradless of compression, the effective displacment stays the same. The piston travels the same distance based on the stroke whether you use long rods or short rods. Or whether the pin height is higher or lower.

But it is true that pin height, ring placement, deck height and alot of other things can effect compression ratio, since each can affect how much volume is squeezed into the combution chamber + the other variables.



<font size=-1>[ This Message was edited by: Beoweolf on 12/2/06 1:33am ]</font>
 

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PS: you could also off set grind the crank. for a little extra stroke.
 

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On top of what Paul said, not only do you see higher skirt loading, but the skirts are typically shorter, too. So you get much more cylinder rocking, and your engine will have a bit shorter life expectancy than a similar power level, higher RPM motor.

<font size=-1>[ This Message was edited by: thekingofazle on 12/2/06 3:14pm ]</font>
 

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Beoweolf,
The stroke is not 3.4 - it is 3.47 and with a normal .030 over bore on a 4" cylinder you get 354.09441 cu". Without the over bore you get close to 350cu" (349 cu&quot
since the Chevy 350 has a bore of 4" and a stroke of 3.48 and give 350 (plus a bit) cubic inches.
"Compression height" is a measurement from the center of the piston pin to the top of the piston. It has no direct bearing on the static compression of the engine but if you have a set deck height and a set stroke you can vary the rod length a little by changing the compression height measurement of the piston. The smaller the compression height is the longer the rod can be. You subtract 1/4" from the compression height, you can add 1/4 inch to the rod length and keep the top of the piston at the same place in reference to the deck.

With the terminology cleared up lets get back to the strokers. Anytime you stroke an engine to get more cubic inches you rob some of the torque it can produce by shortening the rods. This affects HP too because Hp is torque per minute (33000 ft lbs per minute = 1 HP)
You are saving the weight of the larger engine so it kind of washes until you get to the extremes. As you approach the absolute maximum stroke the rod becomes as short as it can be for the stroke. At that point when the crank is producing its maximum torque (90 degrees to the bore) the rod is still putting half its thrust into the wall of the cylinder because the angle is very near 45 degrees. With a long rod engine the angle of the rod is close to 20 degrees. That places only about 25% of the force toward the cylinder wall. You get 50% more torque to the crank at its peak than you do with the short rod engine. That is why when you have the room, the money and the availability of engines it is always better to go with the engine with the longest rod. Even if the compression, bore and stroke are the same, the long rod engine will always produce more torque and more HP while getting better milage and longer life.
There is a 351cu" engine made that will fit in most 302 engine bays with little or no modification. It would be better to build a 351W or Cleveland than to stroke a 302 to 350 cu". You will get more torque and HP from the 351W than you will from the 302 stroked to 351. That translates to more acceleration, faster speeds and lower ET's. You will gain an extra 75 pounds with the larger engine but that 2% increase in weight is offset by the 25% increase in torque and HP. I would take all the 2% increases in weight you wanted to give me if each one came with a 25% increase in HP! How about you?
 

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Your reading too many magazines....


Let me see if I can clarify this a bit. Rod length and ratio means less than nearly anything else within rational limits - no 2" or 8" rods please.
I would be more concerned about paint color than rod length. Torque and power come from cubic inches, cylinder heads, and RPM.
 

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Pauls1950,

So, this additional .007" of stroke required to get to 354 from 347 is going to cause all of the problems you list?

Sorry, I am with BarryR on this one. Get a grip, it's only .007", and by itself is not going to cause a problem with rod angularity.

Piston selection and rod selection, maybe.

Greg
 

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On 2006-12-03 04:19, PaulS1950 wrote:
Beoweolf,
The stroke is not 3.4 - it is 3.47 and with a normal .030 over bore on a 4" cylinder you get 354.09441 cu". Without the over bore you get close to 350cu" (349 cu"
since the Chevy 350 has a bore of 4" and a stroke of 3.48 and give 350 (plus a bit) cubic inches.
Yes, the OP listed 3.47. But he didn't list a reference, a vendor name. So there was no way to confirm what the actual combination is, what was in the kit. With little to go on it's more likely that there was OP error rather than strange configuration.

However, from the nature of the question and the comments following - there seemed to be some confusion about how it was acheived.

There are no off-the shelf cranks spec'ed at 3.47.(none that I know of - unless its cut down from something else) What you can get are 3.0, 3.25 and 3.4 cranks. In the post and another that followed, I qualified the stroke discrepency by accepting that an "off-set" grind, could be used to acheive a 3.47 stroke. I saw no reason to delve into the resulting issues that go along with an odd-ball, non standard stroke; things like finding bearings, sourcing either custom pistons or custom length rods and other geometry changes come to mind.

For a kit that seems to be presented a budget package; thats a lot of custom "stuff"! It is much more likely that the confusion was in mis-quoting the crank stroke.

Custom machine work is not cost-effective for a vendor or kit builder - especially as a popular priced, low cost special.

I did run the number with a 3.47 stroke at the same time;

4.030 x 3.47 would give 354.10
4.040 x 3.47 would give 355.86
4.060 x 3.47 would give 359.39

So there is still some 'rounding' up or down required to get the listed displacment. You have to believe that everything people know or post on a forum subject is not ALL that they know. From how I see it... The point is to inform, not to impress.

But thanks for giving me an opportunity to more fully explain a small part of what went into thinking about the overall answer.

<font size=-1>[ This Message was edited by: Beoweolf on 12/3/06 10:21pm ]</font>
 

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Discussion Starter · #13 ·
thanks for all the good info guys!

this crank is listed on the Eagle web site as the longest stroke for a 302. PAW does have one as well.

i saw one for sale from a private seller and went to look at it. With the price only $150 under retail and the info from you guys I decided to pass on it. Even if the "pushing into side" issue is minor, the price was not good enough to find out.

Today I ordered a DSS 347 pro bullet short block instead.

Thanks again.
 

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On 2006-12-03 04:53, BarryR wrote:
Rod length and ratio means less than nearly anything else within rational limits..............
I would be more concerned about paint color than rod length.
Hopefully, coming from a pro engine builder, this will put the rod ratio "issue" where it belongs.........

Thanks Barry.

P.S. That might even make someone a nice sig quote.
 

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On 2006-12-03 06:50, GregP wrote:
Pauls1950,

So, this additional .007" of stroke required to get to 354 from 347 is going to cause all of the problems you list?

Sorry, I am with BarryR on this one. Get a grip, it's only .007", and by itself is not going to cause a problem with rod angularity.

Piston selection and rod selection, maybe.

Greg
Greg it's not .007 it's .07 but your still right it aint going to make a hill of beans diffrents.
 

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Lunati offered a 349ci kit for a couple years but I' haven't seen it advertised for some time.
 

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what is really the point the 354 kit os going to probabaly be more money then a 347 which are available anyware so you can get parts for them and are you really going to gain hp

jeff
 

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On 2006-12-04 20:01, coolfalcon wrote:
Good catch, I have 007 on the brain ever since the new Bond movie came out.

My mistake, thanks for the correction!

Greg


On 2006-12-03 06:50, GregP wrote:
Pauls1950,

So, this additional .007" of stroke required to get to 354 from 347 is going to cause all of the problems you list?

Sorry, I am with BarryR on this one. Get a grip, it's only .007", and by itself is not going to cause a problem with rod angularity.

Piston selection and rod selection, maybe.

Greg
Greg it's not .007 it's .07 but your still right it aint going to make a hill of beans diffrents.
 

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On 2006-12-03 04:19, PaulS1950 wrote:
With the terminology cleared up lets get back to the strokers. Anytime you stroke an engine to get more cubic inches you rob some of the torque it can produce by shortening the rods. This affects HP too because Hp is torque per minute (33000 ft lbs per minute = 1 HP)
But you're gaining torque by increasing the leverage the rod has on the CENTERLINE of the crankshaft.

On 2006-12-03 04:19, PaulS1950 wrote:
You are saving the weight of the larger engine so it kind of washes until you get to the extremes. As you approach the absolute maximum stroke the rod becomes as short as it can be for the stroke. At that point when the crank is producing its maximum torque (90 degrees to the bore) the rod is still putting half its thrust into the wall of the cylinder because the angle is very near 45 degrees. With a long rod engine the angle of the rod is close to 20 degrees. That places only about 25% of the force toward the cylinder wall. You get 50% more torque to the crank at its peak than you do with the short rod engine.
See my above comment.

On 2006-12-03 04:19, PaulS1950 wrote:
That is why when you have the room, the money and the availability of engines it is always better to go with the engine with the longest rod. Even if the compression, bore and stroke are the same, the long rod engine will always produce more torque and more HP while getting better milage and longer life.
Here I agree, other than that it will 'always produce more torque and horsepower'. Other than that you are correct, until it starts impacting piston compression height.

On 2006-12-03 04:19, PaulS1950 wrote:
There is a 351cu" engine made that will fit in most 302 engine bays with little or no modification. It would be better to build a 351W or Cleveland than to stroke a 302 to 350 cu". You will get more torque and HP from the 351W than you will from the 302 stroked to 351. That translates to more acceleration, faster speeds and lower ET's. You will gain an extra 75 pounds with the larger engine but that 2% increase in weight is offset by the 25% increase in torque and HP. I would take all the 2% increases in weight you wanted to give me if each one came with a 25% increase in HP! How about you?
Hmm, but you're gaining 16-25lbs of rotational mass, almost an inch larger main bearing diameter, then you start adding the weight to the front end of the car...wow. I think it would TAKE a 25% increase in horsepower, which I still don't think you'd get....in order to make UP for that.

I'll make you a deal. You build a 357, I'll build a 347 (I'll spot you the 10ci). We'll use the SAME parts, other than blocks, and in the same car, I'll beat you, every time, guaranteed. This HAS been done, and it holds true.

Something to think about here guys. The ONLY negatives to a 347 is you're maxxed on cubic inches, and block strength over 550hp. Go with a big bore block, and that becomes much less of an issue.

Cris
 

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Joe Sherman has stated he gets more power out of a 347 stroker than a 351w with the same parts.

I think Paul's theory is just that. A theory.
 
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